1. Field of the Invention
The present invention relates generally to gyro apparatus and more particularly to a novel gyro apparatus that effectively utilizes the vibration of an inertial body.
2. Description of the Prior Art
The gyro apparatus of this invention is different in principle from prior art gyro apparatus which are based on various systems. Of these prior art gyro apparatus, a vibration-type gyro apparatus, which is relatively similar to the gyro apparatus of the invention in principle and construction, will hereinafter be described briefly with reference to FIG. 1 as a prior art.
FIG. 1 is a perspective view of such prior art vibration-type gyro apparatus. In the illustrated example of FIG. 1, a tuning fork 1 is attached with a flexible shaft 3 to a base table 2. Displacement detectors 6 and drive windings 4 are mounted on the tuning fork 1 at positions near the upper end thereof. The outputs from the displacement detectors 6 are supplied through a drive amplifier 5 to the drive windings 4 and thereby the vibration amplitude of the tuning fork 1 is kept constant. When an angular velocity .OMEGA. is applied around an axis Z--Z of the flexible shaft 3 of the tuning fork 1, there are generated Coriolis' forces Fc corresponding to the vibration velocity v of the tuning fork 1 and the input angular velocity .OMEGA. and the entire tuning fork 1 is alternately rotated around the axis Z--Z by the Coriolis' forces Fc. That is, a twisting vibration is generated in the tuning fork 1.
According to the prior art example shown in FIG. 1, the twisting vibration of this tuning fork 1 is detected by a twisting detector 8, and the detected output from the twisting detector 8 and the output from the drive amplifier 5 are synchronously rectified by a demodulator 7 to thereby detect the input angular velocity .OMEGA., which is the purpose of the gyro apparatus.
However, in such prior art vibration-type gyro apparatus, the Coriolis' forces Fc generated by the input angular velocity .OMEGA. acting on the vibration body such as the tuning fork 1 and the like are converted to an angular displacement and this angular displacement is detected by the twisting detector 8 so that the prior art gyro apparatus has low detection sensitivity. When a piezo-electric element or like is used as the twisting detector 8, the detection sensitivity is considerably affected by the temperature. Further, since fluctuations of the amplitude of the tuning fork 1 affects directly the sensitivity of the gyro, there must be provided a control system for keeping the amplitude of the tuning fork 1 always constant. Furthermore, since the unbalance of the tuning fork 1 itself causes vibrations around the axis Z--Z and causes a bias error in the output, there are many defects in that the precise balancing of the tuning fork 1 must be established, etc. So, it takes much time to adjust the balance of the tuning fork 1, etc.